![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/Mimas_Cassini.jpg/360px-Mimas_Cassini.jpg)
Mimas is a moon of Saturn. It was discovered in 1789 by William Herschel, after whom the large crater in the image is named. It is the twentieth-largest moon in the Solar System, and the smallest astronomical body that is known to be rounded in shape because of self-gravitation. This photograph of Mimas was taken by the unmanned spacecraft Cassini in 2010.